Frequency determining means



July 11, 1933. RUNGE 1,917,395

FREQUENCY DETERMINING MEANS Filed Oct. 2, 1929 INVENTOR WILHELM RUNGEATTORN EY Patented July 11, 1933 UNITED STATES PATENT OFFICE FURDBAH'IIDBE TELEGRAPHIE M. B. BL,

01? GERMANY OF BERLIN, GERMANY, A CORPORATION FREQUENCY DETERMININGHEARS Application flied Octglger 1929, Serial No.

When a suppressed carrier is boost'ed (restored) in the receiver thefrequency of the booster has to synchronize with that of the suppressedcarrier with the exception of a few cycles. The problem thus results nand amounts to the extensive synchronization of two transmitters. Themost perfect means is the independent synchronism of both transmitters.This method is simpl applicable to telephony on long waves. or waves ofabout 15 meters as they are used today in transoceanic telephony aprecision of about 10' would be required which is not obtam able by themethods hitherto known for producing adjustable constant senders.

Of all the processes wherein a synchronizing frequency emitted by thetransmitter serves to hold the boosted carrier on the correct frequencythe best known comprises the method of emitting jointly the remainder ofa carrier, of workin it through the receiver individually and o settinit therein for heat reception with the booste carrier. The frequency ofthe carrier booster is then to be set by hand or automatically in such away that the beat note will have a itch as low as possible or that itwill drop down to zero.

In transoceanic telephony where the intensity of sound is known to besubject to considerable variations due to the time of the day, anauxiliary tone is emitted besides the voice which tone, being of ahigher pitch than the highest voice frequencies emitted, is kept withinthe limits of constant intensity of sound by a process of automaticallycontrolling the amplification to the effect that the slow hourlyvariations in the intensity of transmission are compensated. In caseswhere only one side band is used for reception with the result that thecarrier and the other side band is being suppressed, whereas the carrieris boosted at the receiving end, this auxiliary tone is transmitted asthe only frequency lying at the distance of its pitch at the side of thecarrier suppressed.

After boosting with an artificial carrier and after demodulation theauxiliary tone will then reappear asan independent frequency. If,however, the boosted carrier varice from the suppressed carrier byn-cycles,

396,895, and in Germany October 15, 1928.

in that case the auxiliary tone, too, after the modulation will vary byn-cycles from the auxiliary tone originally used for modu lation.Accordin to the invention, this auxiliary tone is use to synchronize thecarrier booster. The auxiliary tone, for this purpose, is sent into adevice which, for exam le, actuates a relay in such a way that the re ayis thrown to one side, in case the auxiliary tone has a lower pitch thanits nominal frequency, whereas it is thrown to the opposite side, incase the auxiliary tone has a higher pitch than the nominal frequency.The circuits closed by the relay contacts cause a detuning of theboosted carrier in such a way that the auxiliary tone is tuned up(adjusted) to its nominal frequency. Thereby, however, the auxiliarytone, too, is made to synchronize with the suppressed carrier. Theregulation of the frequency of the auxiliar tone has to be so exact thatthe variations sti 1 existing between the boosted carrier and thesuppressed one may not exceed the allowable limits.

The figure shows a diagrammatic sketch illustrating one embodiment ofthe invention.

The reception coming from the antennae 1 is amplified in the receiver 2,a side band and the carrier are eliminated in case those were emittedalong. By means of the highfrequency generator 3 a carrier correspondingto the suppressed carrier is boosted or restored again to the receiver 2ahead of the rectifier or demodulator in the receiver. The signals thusrectified are sent into two filter chains of which the filter chain 4permits the voice frequencies to ass and conducts them further to thelines E while being impermeable to the frequencies of the auxiliarytone. The filter chain 5 is only permeable to the auxiliary note but notto those of the voice, and furnishes, by way of transformers 6 and 7auxiliary tone potential to the grids of two rectifiers 8 and 9connected in counter-phase. The secondary winding of transformer 6 istuned to the normal frequency of the secondary tone by means of thecondenser 10 and potential oscillations therein act in phase oppositionupon the grids of the tubes 8 and 9. The transformer 7 is not tuned andthe potential oscillations in the secondary winding thereof energizesboth grids in equal phase, since this winding is connected at one end tothe filaments of 8 and 9 and at the other end to the midpoint of thesecondar winding of transformer 6. The potentia s impressed upon thegrids by the transformers 6 and 7 are in phase quadrature to each otherwhen the auxiliary tone is in synchronism with the frequency to whichthe secondary side of the transformer 6 is tuned by the condenser 10.Therefore, the anode currents of both tubes 8 and 9 are equal to eachother, the relay 11 is not energized. If, however, the auxiliary tonefrequency 6 varies from the resonance frequency to which the secondaryside of the transformer 6 is tuned in that case the potentials, at theterminals of the transformer 6 are not out of phase by ninety degrees tothose at the transformer 7. In consequence thereof the one id willreceive a higher alternating potential than the other grid. Therectified currents of the tubes 8 and 9 are therefore of differentmagnitude and the rela 11 will be thrown to the one side or the otheraccording to the direction in which the frequency of the auxiliar tonehas shifted.

When, according to t e connection illustrated, the relay is thrown inone direction the grid of the tube 12 is charged positive by anauxiliary battery 13, whereas the latter is charged negative when therelay is thrown in the opposite direction. The resistance 14 and thecondenser 15 introduce a time lag in the potentials applied to the gridof 12 and varies slowl the potential of the grid of 12 after the gridrelay has been actuated. The anode direct current of the tube 12, thusvaried, is fed a ain to the carrier boosting device and by shifting ofthe carrier boosting frequency to this extent causes correction ofCERTIFICATE OF Patent No. 1, 917,395.

the variation of the auxiliary tone from the nominal frequency.

What I claim is:

1. In apparatus to receive high frequency oscillations which are signalmodulated and also modulated by a super-audible frequency, a receiverincluding a detector, a filter to the super-audible frequency connectedto said detector, thermionic means for producing potential variationsrepresentative of variations in the frequency of the super-audiblefrequency, a high frequency generator connected with said receiver, andmeans for utilizing the potential variations representative of changesin the super-aud1ble frequency for controlling said high frequencygenerator.

2. In radio apparatus to receive high frequency oscillations modulatedby signal frequency and by a control frequency, a radio receiverincluding, a rectifier, means for filtering out the signal fr uencyconnected with said rectifier, an oscillation generator connected withsaid receiver, means for filtering out the control frequency, a pair ofthermionic tubes having input and output electrodes connected inopposition, means for difl'erentially coupling the input circuit of saidthermionic tubes to the output circuit of said control frequency filter,means for cumulatively connecting the input circuit of said thermionictubes to the output circuit of said control frequency, a thermionicamplifier having its input circuits adapted to be connected alternatelyto the terminals of a biasing source by means of a rela connected withthe output circuit of said fi rst named thermionic tubes and aconnection between the output electrodes of said thermionic amplifierand said high frequency generator.

"HELM RUNGE.

CORRECTION.

July 11, 1933.

WILHELM RUNGE.

It is hereby certified that error I, after "filler" to read with thiscorrection therein the case In the Patent Office.

appears in the printed specification of the above numbered patentrequiring correction as followp: Page 2, line 72, claim insert the wordtuned; and that the said Letters Patent should that the same may confomto the record of Signed and scaled thia 5th day of December, A. D. I933.

(Seal) F. M. Hopkins Acting Comiaaioner of Patcntl.

5 to the midpoint of the secondar tential oscillations in the secondarywinding thereof energizes both grids in equal phase, since this windingis connected at one end to the filaments of 8 and 9 and at the other endwinding of transformer 6. The potentia s impressed upon the grids by thetransformers 6 and 7 are in phase quadrature to each other when theauxiliary tone is in synchronism with the frequency to which thesecondary side of the transformer 6 is tuned by the condenser 10.Therefore, the anode currents of both tubes 8 and 9 are equal to eachother, the relay 11 is not energized. If, however, the auxiliary tonefrequency 6 varies from the resonance frequency to which the secondaryside of the transformer 6 is tuned in that case the potentials, at theterminals of the transformer 6 are not out of phase by ninety degrees tothose at the transformer 7. In consequence thereof the one id willreceive a higher alternating potential than the other grid. Therectified currents of the tubes 8 and 9 are therefore of differentmagnitude and the rela 11 will be thrown to the one side or the otheraccording to the direction in which the frequency of the auxiliar tonehas shifted.

When, according to t e connection illustrated, the relay is thrown inone direction the grid of the tube 12 is charged positive by anauxiliary battery 13, whereas the latter is charged negative when therelay is thrown in the opposite direction. The resistance 14 and thecondenser 15 introduce a time lag in the potentials applied to the gridof 12 and varies slowl the potential of the grid of 12 after the gridrelay has been actuated. The anode direct current of the tube 12, thusvaried, is fed a ain to the carrier boosting device and by shifting ofthe carrier boosting frequency to this extent causes correction of thevariation of the auxiliary tone from the nominal frequency.

What I claim is:

1. In apparatus to receive high frequency oscillations which are signalmodulated and also modulated by a super-audible frequency, a receiverincluding a detector, a filter to the super-audible frequency connectedto said detector, thermionic means for producing potential variationsrepresentative of variations in the frequency of the super-audiblefrequency, a high frequency generator connected with said receiver, andmeans for utilizing the potential variations representative of changesin the super-aud1ble frequency for controlling said high frequencygenerator.

2. In radio apparatus to receive high frequency oscillations modulatedby signal frequency and by a control frequency, a radio receiverincluding, a rectifier, means for filtering out the signal fr uencyconnected with said rectifier, an oscillation generator connected withsaid receiver, means for filtering out the control frequency, a pair ofthermionic tubes having input and output electrodes connected inopposition, means for difl'erentially coupling the input circuit of saidthermionic tubes to the output circuit of said control frequency filter,means for cumulatively connecting the input circuit of said thermionictubes to the output circuit of said control frequency, a thermionicamplifier having its input circuits adapted to be connected alternatelyto the terminals of a biasing source by means of a rela connected withthe output circuit of said fi rst named thermionic tubes and aconnection between the output electrodes of said thermionic amplifierand said high frequency generator.

"HELM RUNGE.

CERTIFICATE OF CORRECTION.

Patent No. 1, 917,395.

July 11, 1933.

WILHELM RUNGE.

It is hereby certified that error i, after "filler" he read with thiscorrection therein the case In the Patent Office.

appears in the printed specification of the above numbered patentrequiring correction as followp: Page 2, line 72, claim insert the wordtuned; and that the said Letters Patent should that the same may confomto the record of Signed and sealed thia 5th day of December, A. D. 1933.

(Seal) F. M. Hopkins Acting Comieeioner of Falcon.

